1. Field of the Invention
The present invention is related to radiation shielding, and more particularly, to a magnetic field generator of superconductive material for radiation protection.
2. Description of Related Art
The sun occasionally releases significant amounts of charged particles during events known as coronal mass ejectas (“CMEs”). The charged particles released during CMEs include electrons, protons, and heavy ions. Such proton and heavy ion radiation can cause severe cell damage when humans are exposed to such radiation. Additionally, sensitive electronic components and other devices may be adversely affected by such radiation. Therefore, even though CMEs are relatively uncommon occurrences, the amounts of radiation they could potentially inflict upon a crew and equipment of a spacecraft gives rise for a need to shield part or all of such spacecraft from such radiation. Similarly, a need exists for radiation protection in other environments as well, such as habitats for celestial bodies such as the moon and Mars.
Studies of the time history build-up and decay of CME charged particle flux densities conducted in recent years have lead to the conclusion that CME fluxes are essentially isotropic in nature by the time they reach the vicinity of the earth. These fluxes are thrown out from the sun, immersed in a kind of magnetic field, which acts to bottle up the CME flux, with the energetic particles deflecting off the magnetic structure of the CME plasma, with a mean free path of about 0.04 astronomical unit. Thus, an energetic particle within the CME typically undergoes well over 25 magnetic deflections enroute to the earth, effectively scrambling the directionality of the flux, leading to the requirement that for a shield to be effective, it must provide isotropic protection.
Shielding from proton and heavy ion radiation may generally be accomplished by either absorbing the particles or by deflecting the particles. To absorb the radiation, materials of a thickness sufficient for the amount of energy expected from the radiation, can be provided around an area that houses the crew and/or sensitive equipment during a CME. However, because of the significant amount of weight such a housing would require, the use of radiation absorbing material is not practical for space exploration and other applications. Additionally, the absorption of high energy particles releases a different form of radiation such as gamma rays, neutrons, and X-rays that pass through the shielding material and may harm the crew and/or equipment.
Therefore, it is generally preferred to deflect the particles of radiation rather than absorb them. One example of effective deflection of CME radiation is the earth's magnetosphere which creates a magnetic field of enough flux density to change the trajectory of such radiation particles from the sun or elsewhere, thus causing the radiation to be diverted away from the earth. Therefore, it would be desirable to create an artificial magnetosphere around an area, such as a spacecraft crew compartment, that required shielding from such radiation. However, because of the need to minimize the weight and energy consumption of spacecrafts, systems for creating such an artificial magnetosphere, for even a relatively brief period of time, such as a day or two, have not been practical based upon the amount of material and/or energy required.
A need therefore exists for a radiation shield that is relatively lightweight and that requires relatively little energy.